It is desirable that vehicle-mounted components such as vehicle doors are operated only when the vehicle is securely parked, even while an engine o the vehicle is stopped. In order to allow the operation of the vehicle-mounted components only when an effective shift position is in a parking position in the vehicle with an automatic transmission, it is necessary to keep supplying electricity to an actuator controller for controlling an actuator even while the vehicle is parked and the engine is stopped. This is to detect the effective shift position driven by the actuator at all times via the actuator controller. In this regard, the parking position is a shift position in which there is no transmission between an input side and an output side of the automatic transmission and an output shaft of the automatic transmission is mechanically locked.
A capacitance of a vehicle-mounted battery is limited. Thus, it is desirable to detect the effective shift position without consuming electricity at all or with small electricity consumption while the vehicle is parked, to prevent the battery from running out.
The controller for a vehicle-mounted component has an automatic transmission, a shift position detector, a shift position switching unit, a parking switching unit, a shift position switching controller, a memory device and a vehicle-mounted component controller. The automatic transmission reduces a rotation of an engine and outputs the rotation at an output shaft. The shift position detector detects an effective shift position of the automatic transmission. The shift position switching unit switches the effective shift position of the automatic transmission. The parking switching unit mechanically locks the output shaft of the automatic transmission when the shift position switching unit switches the effective shift position in a parking position. The shift position switching controller controls the shift position switching unit. The current supply to the shift position switching controller is substantially stopped when the engine is stopped. The memory device memorizes the effective shift position at a timing when the shift position switching controller stops being energized. The vehicle-mounted component controller prohibits an operation of a vehicle-mounted component when the effective shift position memorized in the memory device is not in the parking position while the current supply to the shift position switching controller is stopped.